just my 0,02€: I'd stay away from DI machines, with inline plate imaging. they might look like a nice way of having an offset machine seem like a network printer to the casual user but you're basically coupling your slowest device with your fastest (plate imaging does take a while even if the rest is all automated). I'd go for a used ryobi (whatever format floats your boat), with full automation incl. inkwells and what not and "offline" plate imaging.
IMHO a DI is exactly what I would recommend.
I run a 52DI and can not find a single fault with it, we started off with a 34cm press but wanted landscape format and size so upgraded. That was three years ago and we have never looked back, we were originally a komori b2 house but we can run shorter jobs on the DI as well as the longer runs.
I can't see a problem with the 15 minutes it takes to run a set of plates, I use that time to change paper size, set delivery or load the feeder etc, I run from 8am to 4pm and can sometimes get as much as 20 minutes free time in the day! Our shortest runs are about 500 sheets and we go up to 25000 when needed. Makeready is negligible, I can be at ISO12647 colour within 50 sheets on most jobs, we have never had a set of plates come out with mis-register, that is a machine fault and should be fixed. If the operator wastes the 15 mins by wandering around then he is not a very good DI operator.
All our work is 300line and ISO standard matched, I normally run at 6500/hr but on a rush job we run 9-9500/hr all day. We can turn work in about 15-20 mins if needed and printing is enjoyable again since getting rid of alcohol, damper rollers, hickeys, plate changing, registration, paper stretch, long wash-ups and plate processor cleaning etc.
They are not perfect but they are a force to be reckoned with in the right hands. In an average day I will put around 10-12 jobs on the floor ranging from 1000 to 2500 sheets each, I don't think that's too shabby considering they are all quality, colour matched jobs and not flyers or leaflets etc.
Dave